- Primary pathogens (Group A Streptococcus (Streptococcus pyogenes) · Staphylococcus aureus (MSSA) — especially with trauma, wound, or purulent focus)
- Clinical context (Non-purulent cellulitis or phlegmon (diffuse soft-tissue infection without drainable abscess) — IDSA classifies as streptococcal-predominant; MRSA coverage selective per risk factors)
First-line therapy
Cephalexin • p.o. • 25–25 mg/kg/dose • 3×/day
Max 1000 mg/dose · Max 3000 mg/day · Duration: 5 days · CHOP non-purulent pathway: 50 mg/kg/day in 3 doses (max 500 mg/dose) — higher per-dose regimens used for moderate cellulitis (UCSF, AAFP)
Enter weight on Kids to calculate doses
Clindamycin • p.o. • 10–10 mg/kg/dose • 3×/day
Max 600 mg/dose · Max 1800 mg/day · Duration: 5 days · Covers streptococci and most CA-MRSA if susceptible — verify local clindamycin resistance (D-test if inducible resistance concern)
- • Clindamycin: beta-lactam allergy (non-anaphylactic), purulent SSTI with MRSA risk factors, or treatment failure after 48 h on cephalexin/cefazolin — covers streptococci and most CA-MRSA if susceptible (IDSA, CHOP).
- • Amoxicillin/clavulanate: human/animal bite, polymicrobial concern, or beta-lactamase–producing organisms — IDSA oral option for cellulitis (IDSA SSTI 2014, AAP).
- • TMP/SMX (trimethoprim component 8 mg/kg/day divided BID): CPS preferred outpatient monotherapy when MRSA suspected — does not reliably cover Group A strep alone; combine with beta-lactam if dual coverage needed (CPS, IDSA).
- • Vancomycin i.v.: hospitalized child with systemic toxicity, severe phlegmon, or concern for MRSA with clindamycin resistance — CPS inpatient guidance; add clindamycin for toxin suppression in severe S. aureus (CPS, IDSA).
- • IV therapy (cefazolin): unable to tolerate oral antibiotics, moderate–severe systemic signs, facial/periorbital cellulitis, phlegmon requiring admission, or failed outpatient therapy — switch to PO cephalexin when afebrile ≥24 h and clinically improving (CHOP, NICE, IDSA).
Enter weight on Kids to calculate doses
Clinical notes
- • Oral therapy (cephalexin): afebrile or mildly ill child tolerating oral intake, reliable follow-up, no concern for necrotizing infection — IDSA first-line for non-purulent cellulitis without systemic toxicity (IDSA SSTI, NICE, CPS).
- • IV therapy (cefazolin): systemic toxicity, dehydration, failed oral therapy, phlegmon requiring hospitalization, periorbital/facial involvement, or age <3 months — CPS and CHOP pathways; step down to oral when improving (CHOP, CPS).
- • Surgical consultation: suspected necrotizing fasciitis (severe pain out of proportion, bullae, skin necrosis, shock), orbital cellulitis, deep space neck phlegmon, no improvement at 48 h, or progression despite antibiotics — urgent evaluation (IDSA, NICE).
- • Incision and drainage (I&D): required for abscess with fluctuance — purulent SSTI; phlegmon without drainable collection does not routinely need I&D initially, but reassess for evolving abscess at 48 h (IDSA: drainage primary for abscess; antibiotics adjunct if cellulitis).
- • MRSA coverage: add when purulent drainage, penetrating trauma, personal/household MRSA history, failed beta-lactam at 48 h, or severe infection — clindamycin if susceptible, TMP/SMX per CPS for outpatient MRSA; routine MRSA coverage not needed for uncomplicated non-purulent cellulitis (IDSA strong, CHOP, CPS).
- • IDSA — Practice guidelines for skin and soft tissue infections (2014)
- • CHOP — Cellulitis/abscess antibiotic pathway (skin and soft tissue infections) (2024)
- • CPS — Management of community-associated bacterial SSTI in children (2024)
+ 3 more
- • AAP Red Book — Group A streptococcal and staphylococcal skin infections (2024)
- • NICE — Cellulitis and erysipelitis (principles applicable to children) (2022)
- • ESPID — Skin and soft tissue infection guidance (2024)